In Batman: The Last Arkham, Jeremiah is portrayed as the somewhat sadistic administrator of Arkham Asylum who has delusions that the criminals he houses could one day be housed in society. The Asylum had come into Jeremiah's possession after his uncle Amadeus Arkham died after going mad. Jeremiah proceeded to demolish the asylum before rebuilding it with state-of-the-art systems to keep Arkham's criminals, such as The Joker, The Scarecrow and Cornelius Stirk, contained.

Jeremiah's background was touched upon briefly. Although not much is known about his prior history, the issue states that when he was a teenager he walked into a corner store being held up at gun point by an escaped inmate of the nearby Arkham Asylum, which was coincidentally run by his uncle. The gunman had already killed the storeowners, but when he went to shoot him, Jeremiah seemed to know all about the gunman's past and talked the gunman out of shooting him. The gunman then proceeded to commit suicide and Jeremiah knew he would be destined to succeed his uncle as the head of Arkham Asylum.[1]

Soon after the new Arkham is built, Batman stumbles across a series of murders resembling Zsasz's MO. Zsasz (who also debuted in Shadow of the Bat #1) had been an inmate at Arkham Asylum for a long period, but the similarity was too much to ignore, so Batman fakes insanity to get into the asylum to investigate. However, Jeremiah is unaware of this plot and takes Batman's insanity as genuine. Zsasz had actually been the murderer and had been getting out of Arkham by a series of underground tunnels put in place by the contractor on the asylum's revamp. Zsasz, upon hearing of Batman's arrival, predicts it's a set-up and begins to plant seeds of doubt and hatred towards Batman in Jeremiah Arkham's mind. In addition to this, Jeremiah blames Batman for stopping his inmate's rehabilitation. The situation erupts when Jeremiah locks Batman in a room and sets the inmates of Arkham on him, including Amygdala, The Riddler and others.[2]

After the main storyline is wrapped up, and Zsasz uncovered, Batman questions whether Jeremiah is himself mad. Jeremiah denies it, but in the closing scene of the comic, he asks himself whether he will end up like his insane uncle and whether he is indeed mad as Batman suggested.[3]

Jeremiah Arkham returned once again during Knightfall. His role began when he was held at gunpoint by The Joker after Arkham Asylum is attacked by Bane in order to free the asylum's inmates. The Joker attempts to scare Jeremiah into madness and Jeremiah is only saved when Batman frees him from the Joker's trap.[4]

After this story arc, Jeremiah Arkham has appeared occasionally throughout Batman storylines. During Batman: No Man's Land, he opened the Asylum gates, believing it was better for his patients to be at large in a mostly abandoned city than trapped in the Asylum with limited supplies. Most recently during the Batman: Battle for the Cowl, he envisions a plan to rebuild Arkham Asylum, after it was destroyed by himself (as the new Black Mask) following his capture and defeat by the new Batman.[5]

Arkham as Black Mask, destroying his own asylum in Batman: Battle for the Cowl #1. Art by Tony Daniel.

He also starred in the 3-issue follow up, Arkham Reborn, written by David Hine and drawn by Jeremy Haun. The story starts with Jeremiah returning to Arkham Asylum after it has been destroyed by the Black Glove. On his return he finds that some of the patients are still there, including his three 'special' subjects that no one knows about: No-Face, Mirror-Man and the Hamburger Lady. Once back in his office, Jeremiah finds his office a mess, spooky graffiti on the mirror and the journal of Amadeus Arkham (his Uncle) on his desk, though he thought he had burnt it. He finds his uncle's original plans for the asylum and decides it is an omen and thus starts to rebuild according to the plans.

The Asylum re-opens with the disgruntled blessing of the Gotham Shield Committee, consisting of Bruce Wayne (who was Thomas Elliot in disguise), D.A. Kate Spencer and Commissioner Gordon. He is also joined by Aaron Cash (head of Arkham security) and the new assistant director, Alyce Sinner.

As the Asylum gets more complete more accidents happen. The Raggedy Man is set loose, Clayface gets sick, Mr. Freeze's room heats up and Killer Croc's tank filtration breaks. As these events pass, Jeremiah becomes more stressed and unhinged, spending more time with his special patients.

Meanwhile, it is revealed that Alyce is having sexual relations with Black Mask. Once back at the asylum, she uses the computers to project the voice of Amadeus to the inmates and make them riot. Batman then intervenes and gets all the inmates back to their cells. Raggedy Man is found dead and Jeremiah is starting to fall apart. This is all part of the plan of Black Mask. Alyce reports back to him, apparently doing this for the money, and claims she also wants the asylum. Jeremiah works out with Batman's help that Alyce is behind it all and she is committed. When he goes to talk to his special patients for some mental release he is confronted by a scary Jester figure (reminiscent of Joker). It is at this point he loses it. He is found by Batman and locked up with the other inmates in Arkham and Alyce is freed and made Director of the asylum.

In the end it turns out that his special patients were all a delusion and he also suffers with no recollection of when he is the Black Mask. He discovers this when Batman takes him to see the special three and after some intense moments Jeremiah attacks and "kills" them. Filled with remorse, Jeremiah is confronted with videotape of what had just occurred, courtesy of cameras hidden by a suspicious Cash. The video shows only himself, talking and attacking hallucinations. He then completely breaks down and breaks the Jester staff which lets out a gas. Upon awakening, Jeremiah remembers everything - during his sessions with inmates Hugo Strange (a master of chemicals and psychology) and Joker, he had been given the Jester's staff, revealed to be coated in a chemical making the user very vulnerable to hypnotic suggestions. Strange and the Joker both manipulated Jeremiah, assaulting his weakened psyche: Strange encouraging an appetite for power and respect (resulting in the Black Mask personality), Joker encouraging his own style of insanity (manifesting as the Jester). Claiming to be back in control, Jeremiah is then put in intensive care. Zsasz, who had threatened him earlier, comes to kill him and mark the scar inside his eyelid to remember him by. But by the time help arrives, Jeremiah has tied up Zsasz and delicately carved his initials there himself, proving the Black Mask is far from gone.

Jeremiah Arkham is locked up and left in the care of Alyce. He confesses to her that he is Black Mask and Zsasz is proof. She then kisses him and they embrace, Jeremiah pictured as the Black Mask.[6] It remains to be seen if Jeremiah's heavy exposure to the chemical in the staff merely made the Black Mask personality dominant, or if it has absorbed the others completely.

In The New 52 (a reboot of the DC Comics universe), a character resembling Jeremiah Arkham's incarnation of the Black Mask was seen early on during an Arkham Asylum Breakout in the Night of the Owls storyline. However, Jeremiah Arkham was later seen in charge of Arkham Asylum instead of Alyce Sinner and not incarcerated within the building's cells. Despite this, his history as the Black Mask was still intact. He is seen congratulating Batman's decision on bringing the Joker to the asylum where he can receive "treatment" instead of dropping him off at a prison. Later during the Night of Owls event, Arkham is seen targeted by Talons as well as treating Roman Sionis, the first Black Mask. Sionis confirms Arkham's having been the Black Mask during Richard Grayson's time as Batman before Arkham is attacked by Talons. Arkham uses a Taser to fight off the Talons before being rescued by Batman.[7]